Electric switch



Sept. 7, 1943. w. A. ATWOOD' 2,328,942

ELECTRIC SWITCH 7+-- Whfmceld ANC 0061, by WWE* y His Attorney.

Spt. 7, 1943. w. A. ATwooD 2,328,942

ELECTRIC SWITCH Filed April 24, 1942 2 Sheets-Sheet 2 Inventor: Wirw'elci A Atvvoocl,

by Mm ttorrwey.

Patented Sept. 7, 1943 UNITED ELECTRIC SWITCH Winfield A. Atwood, Yeadon, Pa., assigner to General Electric Company, a corporation of New York Application April 24, 1942, Serial No. 440,296

(Cl. Zilli-89) 17 Claims.

My invention relates to improvements in electric switches and more particularly high speed circuit breakers and especially circuit breakers for interrupting a direct or rectified alternating current circuit, whose current is increasing at a high rate, before the magnitude of the current can attain dangerous values.

Probably the greatest trouble experienced in the operation of mercury arc rectillers arises from abnormal operating conditions such as an arc-back occasioned by reverse current iiow from cathode to anode or by the striking or" an arc discharge between anodes. The reversal of current flow establishes a short circuit which is fed not only by the other rectiying paths of the particular rectiner, but also by all the rectiliers operating in parallel with this rectiiier. The rate of increase of current in this short circuit path is so high, particularly in large installations, that currents dangerous to equipment and personnel and destructive of service continuity are quickly reached. There have been observed rates of increase ci current of over six million amperes a second for a single rectifier and over eleven million amperes a second where several are operated in parallel. It is, therefore, imperative to interrupt this short circuit current very quickly if the current at interruption is not to exceed a safe value and interruption of service is to be prevented. In short, the problem is to interrupt the circuit of the faulty anode so quickly as to limit the resulting current to a safe value. Moreover, this must be accomplished with apparatus which is not only dependable, but also economically feasible. Also, in the starting operation of mercury arc rectiiiers, either initially or after a shutdown, it is customary to degas or bake out the rectifier for a period of time. During this period, safety to equipment and personnel requires that the means used to interrupt the anode circuit be positively maintained in the open circuit position.

@ne object of my invention is to provide an improved circuit breaker, the inertia of the movable parts oi which is reduced to a minimum consistent with the required current carrying and interrupting capacity, and the arrangement; of the parts of which is such as to facilitate a quick circuit opening operation. Another object of my invention is to provide an improved circuit breaker mechanism such that any one or more of a group of poles can be operated to the circuit closing position either manually or by a single motive power means without interfering with the closed poles and such that each pole is trip-free and independent of the others as far as interruption is concerned. Still another object cf my invention is to provide a circuit breaker mechanism which can be operated by suitable motive lpower means or manually, as desired, and yet readily placed in a condition positively to prevent the circuit closing operation. A further object of my invention is to provide an improved circuit breaker which will open so rapidly that it will limit and interrupt a current flowing through its closed contacts at a high rate of increase and in a predetermined direction before the magnitude 0f the current attains an unsafe value. A still further object of my invention is to provide an improved high current capacity circuit breaker having a simple but sturdy structure, capable of severe duty and yet economically feasible from the standpoint of installation, operation, and maintenance. These and other objects of my invention will hereinafter appear in more detail.

In accordance with my invention, I reduce the weight of the moving parts of the circuit breaker structure and the friction between them to a minimum so as to obtain the quickest opening consistent with the necessary current carrying and interrupting capacity. Also, in accordance with my invention, I provide a latched closed type of circuit breaker mechanism e-mbodying the minimum number of operating parts, which are so arranged as to permit a quick opening movement of the circuit breaker contacts upon release of the latch. Further in accordance with my invention, I provide a high speed trip mechanism which is normally electromagneticaily held against a strong bias, the effect of which is immediately available for tripping under predetermined conditions oi current now through the circuit breaker contacts. Likewise, in accordance with my invention, I provide means operative during the opening movement o1" the circuit breaker to restore the latching mechanism to the holding position against its bias and to maintain it in the holding position as long as the circuit breaker is open and also while the circuit breakker is closed and providing the direction of current flow through its contacts is normal. Also, in accordance with my invention, I provide a circuit breaker structure such that in a grouping of two or more units or poles, any one or more of the poles can be closed independently ci the others by a simple manual or motive power device witn each pole free to open at any time independently of any of the others.

My invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying two sheets of drawings, Fig. l is a vertical side elevation, partly broken away and partly in section of a circuit breaker embodying my invention; Fig. 2 is a fragmentary view illustrating certain of the parts at the instant of tripping. Fig. 3 is a partial View similar to Fig. l showing an intermediate position of the parts during the circuit opening movement thereof; Fig. e is a view similar to Fig. 3 showing the circuit breaker parts in the full open position and ready to start the closing operation; Fig. 5 is a View similar to Figs. 3 and e illustrating the closing operation partially completed; Fig. 6 is a diagra' illustrating how certain of the parts are arranged to maintain the breaker in the closed position; Fig. 7 is a part sectional view on the line i-'l of ig. l with one part reversed in position; Fig. 8 is a fragmentary View of a modification of the means used to hold the circuit breaker in the closed position; and Fig. 9 is an elevation to a larger scale of a contact mounting detail.

In the illustrated embodiment of my invention, a bascor panel of suitable insulating material has suitably secured thereto spaced lower and upper` contact studs l I and I2, respectively, which are provided with terminals I3 and I4, respectively. The stud iI comprises a stationary contact blocl; i5 having a curved contacting surface I5, which is preferably cylindrical for reasons presently to appear. The stud I2 comprises a contact block Il in which is supported a plurality of relatively stationary contacts I8, only one of which appears in the drawings. Each of such contacts i8 is arranged for high pressure line contact with the stud block Il. For this purpose, each contact i8 is mounted with its upper end tting somewhat loosely in a cylindrical recess I9 in the stud block il. As shown more clearly in Figs. 1 and 9, the mounting for each contact I8 includes a headed screw 2E) which is supported in an opening in the stud I2 and screwed into the block. E?. ln order to maintain a sharp current loop at the contact recess IS, the head ofthe screw 2G is ce' tered in the opening of the stud I2 by suitable insulating means such as a bushing M to prevent the passage of current from the LU block i? through the screw 23 and the spring 2I to the stud I2. The screw 23 carries a backing spring 2i, the bias of which holds the upper end 22 of the contact I8 forward against the face of the recess EQ in line-to-line contact. For better contact action, the upper end of the contact IB and the surface of the recess i9 against which it bears may be silver faced. Likewise, the lower end of the contact I8 may be provided with a silver Contact piece 2S.

For completing a circuit through the circuit breaker, there is provided a contact 24, which is ulcrumed on the curved contacting surface I6 of the stationary contact I5 for movement into engage-ment with the relatively stationary contact I8 by a mechanism constructed in accordance with my invention so as to insure high speed circuit ocening action. In the arrangement illustrated, the lower end of the contact 24 is pro-vided with a plane contact surface 25 which fulcrurns on the cylindrical contact surface I6 of the contact blccl; I5. Both of the contact surfaces I G and 25 are preferably silver faced for better contact action. At an intermediate point in its length, the movable contact 24 is provided with a silver contact portion 2S, which is arranged to engage the silver portion 23 on each of the contacts l. The contacts I3 are spaced slightly by separators 2l' in order that each may be free to move independently of the others under the magnetic attracting for es between them due to the currents flowing through them in the same direction and thus come to a better bearing in the contact recess i9 and against the contact face 26 of the movable contact 24. The separators 21 are preferably not of magnetic material but suit- `ots as a line contact.

able insulating material may be used. In addition to the primary stationary contacts I8 there is also provided a secondary or arcing stationary contact 28 whose upper end is mounted in a cylindrical recess Ell in an arcing Contact block 3U separated from the contact block il by suitable insulation. Lilie the primary stationary contacts I8, the secv .ifiary stationary contact 28 is biased forward to engage the arclng contact block 30 in line-to--linccontact. For this purpose, there is provided suitable means, such one or more backing springs which are mounted in holes in the stud I2, The backing springs SI do not engage the contact 23 directly but are spaced therefrom by insula g rods 32. The lower end ol? the seco idary sta onary contact 2B and the upper end of the movable contact 2-1 are provided with suitable contact portions 33.

For arc extinguishing purposes, the arcing contact block 3G is provided with an arcing horn extension 34 and is, connected to the stud I2 through a blowout coil 35. For carrying the end of the are ori from the contact portion 33 of the ovable contact 24, there is provided a blowout coil 3B with suitable core, the coil 35 being connected between an arcng horn 37 and the lower stud II of the circ Vt breaker. The connection to the lower stud is broken away in Fig. l for the purpose of clearness of illustration of the breaker mechanism. The arc extinguis ng structure furthur includes pole pieces (not shown) for the core in coil and tira/o enclosing barriers 38, only one of which appears in the drawing.

In order that the plane face 25 of the movable bridging contact 24 may pivot on the cylindrical face I6 of the Contact block I5, I mount the contact 24 on suitable supporting means, such as a cradle, pivoted to rotate about an axis which is substantially in line with the element of the cylindrical surface I5 about which the contact piv- In other words, the construction is such that the pivotal axes of the contact 24 and the cradle are as nearly coincident as possible in order to reduce the sliding between and consequent wear ci the contact surfaces I6 and 25 to a minimum. As shown, this cradle comprises two spaced side members 39, only one of which appears in the drawing. Each of these is supported on a pivot 40 mounted in the side 4I of the circuit breaker frame adjacent the side member of the cradle. At the upper end, the side `members 39 are joined by a pivot 42, which passes through the contact 24 and leaves this contact free to be biased against the contact surface I6 and for high speed of opening operation. It is here noted that in the circuit closed position of the Contact structure described, the magnetic loop expansion effect produced by any current through the circuit breaker increases the pressure between the contacts long as the cradle 39 is maintained in the circuit closing position and, consequently, tends to accelerate contact separation when the cradle is free to rotate clockwise about its pivot 4U.

In order to move the cradle 39 into and maintain it in the circuit closing position and yet have it quickly freed for high speed interruption,-I provide a movable abutment 43, relcasable means comprising a latch 44 pivoted in the frame 4I at 44 for holding the abutmentv 43 in a predetermined position, and actuating means comprising a member 45 movable on the abutment 43 and between the abutment and a member 46 movable with the bridging contact 24, for examplefpivoted on the cradle 39. In order to minimize friction and facilitate high speed operation, the members 45 and 46 are preferably rollers, as shown. The abutment 43 is mounted on a pivot 41 extending between the sides 4| of the circuit breaker frame. In order to obtain the counterclockwise movement of the cradle 39 necessary to bring the contact 24 into the normal current conducting position, the abutment is provided with a suitably shaped cam face 48, which is traversed by the roller 45. The roller 45 is thus movable between a surface 46 movable with and relatively to the bridging contact and the opposing cam surface 48 of the movable abutment and on this cam surface. For actuating the roller 45, I provide an operating member 49, which, as shown, is mounted on the pivot 41 and is connected to the roller 45 through one or more operating links 50. These links are pivoted to the operating member 49 at 5I and to the roller 45 at 52. The operating member comprises two side pieces 49 and a cross connection 53, which in the closed position of the circuit breaker abuts the frame 4l at 54, as shown in Fig. l. In order to maintain the circuit breaker in this closed position as long as the abutment 43 is maintained in the latched position, the parts are so proportioned and arranged that in the closed position of the circuit breaker, the direction of pressure on the roller 45 tends to force this roller to the right on the cam surface 48. This will be more clearly understood from a consideration of Fig. 6 wherein the direction A of the pressure tending to open the circuit breaker passes through the centers of curvature of the rollers 45 and 46 and intersects the cam surface 48 at a point just sufiiciently to the right of the line B through the centers of curvature of the roller 45 and the cam surface 48 to provide the necessary holding bias.

For releasing the latch 44 so as to effect the opening of the circuit breaker, I provide electromagnetic means responsive to a predetermined abnormal condition of the circuit controlled by the circuit breaker. The particular means illustrated is responsive to a predetermined direction of flow of direct current. As shown, this means comprises two U-shaped cores 55 and 56 of suitable magnetc material arranged substantially perpendicularly to each other and having two common polar extensions 51, only one of which appears in the drawings, with an air gap arranged to be bridged by an armature 58. The core 55 is secured to the frame 4I so as to embrace the stud I I and is accordingly energized responsively to the magnitude and direction of the current flowing through the circuit breaker. The core 56 is energized by polarizing windings 59, one on each leg of the magnet and energized preferably from a source of direct potential although rectified alternating current may be used. The flux of these polarizing windings alone is sumcient to maintain the armature 58 in the attracted position against the bias of a latch actuating spring 60s which pushes against the tail of the latch 44 through a collared rod 6| passing through the armature 58. A turned down portion of the rod 6| passes through the armature 58, the shoulder on the rod where the diameter is reduced being employed to move the armautre 58 away from the magnet pole faces because of the bias of the spring 66 on the occasions of predetermined current conditions in the breaker. The magnetic structure and arrangement is such that when current flows through the circuit breaker in a predetermined direction the flux due to the current is additive in its effect to the armature holding effect of the flux due to the windings 59. However, when current ows through the circuit breaker in a direction opposite to said predetermined direction, the two fluxes not only are subtractive in their resultant holding effect, but also are so shifted that the armature 58 is quickly released to trip the latch 44 under the action of the spring 60. The bias of the spring may be controlled by a nut 62 threaded on a spring support 63, which may also serve to secure the removable bottom of the U- shaped magnetic structure to the stud Il, as shown. The weight of the armature 58 and the movable parts directly associated therewith is reduced to a minimum in order to expedite the circuit opening action of the circuit breaker.

For resetting or returning the armature 58 to the attracted position during the opening of the circuit breaker, I provide means responsive to the movement of the abutment 43. As shown, this means comprises a link 64 pivoted at 65 to the abutment 43 and to the latch 44 at 66 through a slotted opening B1, the purpose of which is to allow a desired counterclockwise movement of the abutment before resetting the armature. In order to prevent undue shock to the armature 58 during the resetting movement, I provide a shock absorbing spring 63 around the stern of the rod 6i the side of the armature away from the polar extensions 5l. The plug 69, screwed into the frame, provides a shoulder' stop for armature 58 so that the latter may not compress the spring 5.28 to its solid height as the armature moves and thereby strip the collar l0 secured to the rod SI therefrom. For resetting the abutment 43 and the latch 44 to the sustaining position, I provide abutment return springs 7i and a latch return spring l2. The former is secured to the abutment pivot 55 and to the frame 4l and tends to turn the abutment clockwise about its pivot 4l'. The latch return spring 'i2 is connected between the latch 44 and the frame 4I and tends to turn the latch clockwise about its pivot 44'.

For effecting a quick movement of the contact 24 to the circuit opening position, exerting pressure between the contact surfaces I5 and 25 at al1 times, and also recompressing the tripping spring 68, I provide suitable energy storing means, such as biasing springs '13, only one of which appears in the drawings. These springs are positioned outside of the cradle 39. In order to have them suitably stressed during the closing movement of the breaker, they are connected between a stud 74 supported in the sides of the frame 4l and a rod l5 fixed in the movable contact 24 but extending through slotted openings, not shown, in the cradle sides 39 so as to permit a, predetermined movement of the contact 24 relatively to the cradle 39. For exerting pressure between the contact surfaces i6 and 25 at all times and also returning the operating member 49 and the parts connected thereto to the position shown in Fig. 4, I provide suitable energy storing means, such as a biasing spring In order to have this spring suitably stressed during the closing movement of the circuit breaker, it is connected between the pivot 5l and a rod 16' fixed in the contact 24 which is provided with a, hollow portion for receiving the end of the spring.

Since mercury arc rectifiers usually have six anode circuits and sometimes more, I provide an arrangement whereby a plurality of singlepole circuit breakers in the open circuit position can be closed simultaneously, and also any one r more poles can open and can be closed without interfering with the poles that are closed whereby to avoid unnecessary interruptions in sound anode circuits. For this purpose, I provide each pole with an actuating lever l1 pivoted at 41 and then interconnect these levers byva common actuating means comprising a crossbar 18. As shown, the actuating lever T is U-shaped with a cross piece 'i having a projection 80 arranged to abut the cross piece 53 of the operating crank 4S. In order to insure that each pole will be positively closed, I adjustably position the projection Sii so as to take care oi` manufacturing tolerances and variations in lost motion whereby to insure the desired closing action of any one or more poles even though the others are closed. The projection 8U is so adjusted that a predetermined clockwise movement of the actuating lever il will impart suihcient clockwise movement to the operating crank 49 to effect the holding bias of the rollers, as explained in connection with Fig. 6. This, in general, will cause the operating crank to settle with its cross piece 53 abutting the frame di at 54 with some clearance between the projection Si) and the cross piece 53. However, it is possible that the final holding biased position or the crank 9 may be reached at the end oi the clockwise movement of the actuating lever 1T. in this case, the projection 8G may continue to abut 'the operating crank cross piece 53.

For actuating the crossbar 'i3 to close the circuit breaker pole units, I provide a motive power mechanism, which is also adapted to manual operation. As shown, this mechanism comprises a. motor-driven mechanism of the type disclosed in United States Letters Patent 2,034,145, issued March 17, 1936, and assigned to the assignee ci this invention. rhis mechanism comprises an electric motor provided with a hand wheel 82 mounted on its shaft and arranged to drive through a gear mechanism, not shown, a. cam 83 of suitable contour. The motion ci this cam is imparted to the crossbar 'i8 through a crank 84 pivoted at in the mechanism frame 83 and connected to the crossbar through a connecting rod 87 at pivotal points t and the latter being in bracket piece secured to the crossbar 7S. The crank is pro-vided with a socket portion Si for the reception of a suitable lever or rod 9i whereby the closing operation may be manually performed. For raising the crank 82, the connecting and the actuating levers 11 to a position which permits resetting the cperating crank A249 and parts connected thereto in order to close the circuit breaker, I provide retrieving or raising moans, such as one or more springs 93 connected between the motor mecha nism frame at Gti and the crank Si; 8b' in such a way as to eXcrt upward thrust on the connecting rod Si" when the cam G3 is turned counterclockwise sufficiently to permit counterclockwise movement oi the crank Si In order Ivent a closing oper on oi the circuit b or example, it isl desired to work on ctifre thereof or apparatus whose circ i lled by the circuit breaker, proi preventing move lent of the 1. ossb i r by the motor 8i or manualiy. As shown in Figs. l and 7, this means comfrises a control member 96, which can be positioned in the side of the operating mechanisni frame BE in two ways. one ci which, -as

shown in Fig. 1, will permit the closing operation, and the other of which, as shown in Fig. 7, will prevent the closing operation. For the latter purpose, one end of the control member 96 has a projection 91, which when the member is screwed into the frame 86, preferably above the projection 98, as shown in Fig. 7, projects into the path ofmovement of a lug 98 on the mechanism crank 84 so as to prevent counterclockwise movement thereof from the position shown in Fig. 1. As the springs S3 cannot lift the crank 84 and the parts attached thereto from the normal down position with the projection Si assembled as described, it will be impossible to close the circuit breaker, although the motor 8l itself may be run through its operating cycle. If the control member is screwed into the frame with the projection 91 inside, as shown in Fig. '7, while the mechanism crank 84 is in the upper position, that is, with the lug S8 above the projection 9i, then the crank 84 cannot be turned clockwise suciently to close the circuit breaker.

Assuming the circuit breaker closed with the parts positioned as shown in Fig. 1 and current flowing through the circuit breaker in the direction which causes the uX of the electromagnet 55 to assist the iiux of the polarizing electromagnet 56 to hold the armature 58 in the attracted position against the bias of the tripping spring 60, then, if the direction oi` the current owing through the circuit breaker is reversed as in the case of an arc-back in the anode circuit of a mercury aro rectifier, the armature is quickly released because of flux opposition and shift in the common magnetic path including the air gap bridged by the armature. The effect of the strong tripping spring 6U is to move the latch 44 i'orcibly counterciockwise about its pivot 44 thus releasino the abutment 43, and momentarily the parts assume the position shown in Fig. 2. Since there is no longer any support for the left-hand or iree end of the abutment 43, the tension of the opening springs i3 and to a certain extent, the springs 'l and the contact springs 2l and 3| together with the weight of the parts bearing on the abutment 43 forces this member to turn in a counterclockwise direction about its pivot 4i whereby quickly to eii'ect the opening of the circuit breaker with the parts positioned as shown in Fig. 3. In this position, the bias on trie roller 65, Which was away from the panel -J, that is in a direction to hold the circuit breaker closed, is now directed toward the panel. If, after the opening of the circuit breaker, manual or automatic means are utilized to energize the circuit of the motor 8i or the hand wheel 82 is turned suiiicientiy in a direction to rotate the cam 83 counterclockvvise, as viewed in Fig. 1, then the crank S- will be iree to rotate counterclockwise about its pivot under the tension of the retrieving springs S3, thus raising the crossbar 8U to the position shown in Fig. 4 with the actu ating lever 'i7 turning ccunterclockwise about its pivot 4?, While this motion is going on, the remaining tension on the spring I6 turns the operating crank 49 counterclockwise about its pvot 41 so that the roller d5 under its bias toward the panel moves to its lowest position on the cam surface A48 of the abutment 43, During this movement, the abutment 43 and its sustaining latch 44 are returned to the latching position under the biasing actions of their respective springs il and l2. In other words, the circuit breaker mechanism is reset as shown in Fig. 4 and ready for the actual closing movement to the position shown in Fig. 1. As the cam 83 continues to turn coiinterclockwise under the action of the motor 8l or rotation of the hand wheel 82, the crank 84 is turned clockwise about its pivot 85 and through the connecting rod B1, turns 'the actuating crank 11 clockwise about its pivot 41. With this movement of the actuating crank, ythe projection 80 engages the transverse portion 53 of the operating crank 49, as shown in Fig. 5, to rotate this member clockwise about its pivbt 41. As this motion takes place, the roller 45 travels along the cam surface 48 in contact with the roller 46 to force the cradle 39 to turn counterclockwise about its pivot 40 yand thereby to eiIect the engagement of the contact 24 with the contacts I8 and 28. During this movement, the springs 13 and 'I5 are stressed in preparation for the next opening action and also to maintain the desired contact pressure between the contact surfaces I6 and 25. The parts are then again in the circuit closing position, as shown in Fig. 1. When a plurality of circuit breaker poles are under the control of the crossbar "I8, each pole that opens during the movement of the crossbar will be closed by the downward movement thereof provided the mechanism of the opened pole can move from the position shown in Fig. 3 to the reset position shown in Fig. 4 before the movement of the crossbar has proceeded so far as to prevent such resetting action. If with the breaker open at any time it is desired to prevent a closing operation, then the control member 95 may be reversed from the position shown in Fig. 1 to the position shown in Fig. '7 so that the projection 91 of this member is above the lug 98 on the crank 84.

Instead of holding the co-ntact 24 in the circuit closing position by the roller biasing arrangement described in connection with Figs. 1 and, I may s o arrange the parts, as shown in Fig. 8, that the line of pressure A tending to open the circuit breaker passes through the centers of curvature of the rollers 45 and 45 and intersects the cam` surface 48 at a point just suiiiciently to the left of the line B' through the centers of curvature of the roller 45 and the cam surface 48 to bias the contact 24 to the circuit opening position. Then in order to hold the contact 24 in the circuit closing position, I provide a latching member S9 pivoted on the frame 4l at lili) and arranged to engage a suitably shaped latching` edge ron the cross member 53 of the operating crank 49. The latch 99 is biased for clockwise movement about its pivot [ou to the latching position shown by suitable means, such as a spring lill. The clockwise movement of the latch 99 is limited by having the tail of the latchabut the frame 4| as shown. In this modification of my invention, the latch 99 is released during the counterclockwise movement of the abutment 43, the tail portion 43 of which strikes the tail portion of the latch 99 to free it from the operating crank t9. Also, in this modification of my invention, I have shown a slightly different biasing means for resetting the latch 44 and the abutment 43. As shown, this means comprises an abutment retrieving spring IGZ, the right-hand end of which connected to the abutment at |03 and the left-hand end of which is connected to the frame 4l. The resetting means also includes a spring m4 which is connected between the abutment 43 at ID3 and the latch 44 at m5. The operation of this modication of my invention will be obvious from the foregoing taken in connection with the description of the embodiment of my invention shown in Fig. 1. f

While I have shown and described my invention in considerable detail, I do not desire to be limited to the eXact arrangements shown, but seek to cover in the appended claims all vthose modifications that fall within the true spirit and scope of my invention. y l

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising pivotally supported contact, a cooperating contact, and means for moving said pivotally supported contact into engagement with said cooperating contact comprising a first roller mounted to move with said pivotally supported contact, a member having a surface of a predetermined contour, and a second roller movable over said surface and between the surface and said iirst roller to effect the circuit closing movement or pivotally supported Contact.

2. yAn electric switch comprising a relatively stationary Contact, a pivotally supported contact movable into engagement with said stationary contact, a first roller movable with said pivotally supported Contact, a movable abutment, means for holding said abutment in a predetermined position, and actuatingr means for ,moving the pivotally supported contact into engagement with the stationarykcontact when the abutment is in said predetermined position comprising a second roller movable on said abutment and between the abutment and said iirst roller. y

3. An electric switch comprising a plvotally supported Contact, a cooperating contact, and means for moving said pivoted contact into engagement with said cooperating contact comprising a rst roller mounted to move with said pivotally supported contact, an abutmenthaving a surface of a predetermined contour, means for holding said abutment in a predetermined position relatively to the circuit closing position of said pivotally supported contact, a second roller movable in one direction over said surface and means for moving said pivotaliy supported con-r rtact into circuit closing engagement with said cooperating contact comprising a first roller.

mounted to move with said pivotally supported Contact, an abutment having a surface of a predetermined contour, releasable means r:for holding said abutment in a predetermined position, a

second roller movable in one direction over the surface of said abutment between the abutment and said iirst roller to effect the circuit closing engagement of said contacts when the abutment is held in said pretermined position, and meansv adapted to be operated to effect the movement of said second roller.

5. An electric switch comprising a pivotally supported contact, a cooperating conta-ct, and means for moving said piv-otally supported contact into circuit closing engagement with said cooperating contact comprising a first roller mounted tomove with said pivoted contact, an abutment having a surface of a predetermined contour, releasable means for holding said abutment in` a predetermined position, a second roller movable in one direction over the surface of said abutment between the abutment and said rst roller to'eiect the circuit closing engagement of said contacts when the abutment is held in said predetermined position, and means adapted to be operated to effect the movement of said second roller, said second roller being positioned relatively to said first roller and the surface of said abutment when said contacts are in normal current conducting engagement to maintain said engagement while said abutment is held in said predetermined position.

6. An electric switch comprising two relatively stationary contacts, a bridging contact fulcrumed on one of said stationary contacts for movement into. engagement with the other stationary contact, a first roller mounted to move with said bridging contact, a movable abutment, means for holding said abutment in a predetermined position, and actuating means for movingthe bridging contact into engagement with said other stationary contact when the abutment is in said predetermined position comprising a second roller movable said abutment .and between the abutment and said iirst roller.

7. An electric switch comprising two relatively stationary contacts. a bridging contact fulcrumed on .one of said stationary contacts for movement into engagement with the other stationary contact, a surface movable with and relatively to said bridging contact, a movable abutment having a surface opposed to said movable surface, releasable means for holding said abutment in a predetermined position, and actuating means for moving the bridging contact into engagement with said other stationary contact when the abutment is in said predetermined position comprising a member movableon saidabutment surface and between the abutment surface and said movable surface, said member being positioned when the bridging Contact is in normal current conducting engagement with the stationary contacts to maintain said engagement whilesaid abutment is held in said predetermined position.

8. An electric switch comprising two relatively stationary contacts, a bridging contact fulcrumed on one of said stationary contacts for movement into engagement with the other stationary contact, a surface movable with and relatively to said bridging contact, a movable abutment having a surface opposed to said movable surface, releasable means for holding said abutment in a predetermined position, actuating means for moving the bridging contact into engagement with said other stationary contact when the abutment is in said predetermined position comprisinga member movable on said abutment surface and between the abutment surface and said movable surface, said member beinfy positioned when the bridging Contact is in normal current conducting engagement with the stationary contacts to maintain said engagement while said abutment is held in said predetermined position, means in which energy is stored during the movement of the bridging contact into engagement with said other stationary contact for quickly effectingr movement or the bridging contact away from said other stationary contact upon release of said holding means, and means for effecting the release of said holding means.

9. An electric switch comprising two relatively stationary contacts, a bridging contact fulcrumed on one of said stationary contacts for movement into. engagement with the other stationary con-- tact, a. surface movable with and relatively to said bridging contact, a movable abutment having a surface opposed to said movable surface, releasable means for holding said abutment in a predetermined position, actuating means for moving the bridging contact into engagement with said other stationary contact when the abutment is in said predetermined position comprising a member movable on said abutment surface and between the abutment surface and said movable surface, means for maintaining the bridging contact in normal current conducting engagement with the stationary contacts while said abutment is held in said predetermined position, means in which energy is stored during the movement of the bridging contact into engagement with said other stationary contact for quickly effecting movement of the bridging contact away from said other stationary contact upon release of said holding means, and means for effecting the release of said holding means.

l0, An electric switch comprising two relatively stationary contacts, a bridging contact, means supporting said bridging contact in pivotal engagement on one of said stationary contacts and for movement into and from engagement with the other stationary contact, a pivotally mounted element having a cam surface of a predetermined contour, releasable means for holding said element in a predetermined position, a first roller mounted on said supporting means, actuating means comprising a second roller movable on said cam surface between the surface and said first roller and means adapted to be operated to move said second roller on said cam surface in a direction to effect engagement of said bridging contact and said other stationary contact when said element is in said predetermined position, means for maintaining said bridging contact in normal current conducting engagement with said stationary contacts while said element is held in said predetermined position, means in which energy is stored during the movement of the bridging contact into engagement with said other stationary contact for quickly effecting movement of the bridging contact away from said other stationary contact upon release of said holding means, and means energizable to effect the release of said holding means.

11.` A electric switch comprising two relatively stationary contacts, a bridging contact, means supporting said bridging contact in pivotal -engagement on one of said stationary contacts and for movement into and from engagement with the other stationary contact, a pivotally mounted element having a cam surface of a predetermined contour, releasable means for holding said element in a predetermined position, a first roller mounted on said supporting means, and actuating means comprising a second roller movable on said cam surface between the surface and said first roller and means adapted to be operated to move said second roller on said cam surface in a direction to effect engagement of said bridging contact and said other stationary contact when said element is in said predetermined position, the position of said rollers relatively to each other and to the cam surface of said element when the bridging contact is in normal current conducting engagement with both of the stationery contacts being such as to maintain such engagement while said element is held in said predetermined position.

12. An electric switch comprising two relatively stationary contacts, a bridging contact,

means supporting said bridging contact in pivotal engagement on one of said stationary contacts and for movement into and from engagement with the other stationary contact, a movable abutment, releasable means for holding said abutment in a predetermined position, a rst roller vmounted on said supporting means, and actuating means comprising a second roller movable on said abutment between the abutment and said first roller and means adapted to be operated to move said second roller on said abutment in a direction to effect engagement of said bridging contact and said other stationary contact when said abutment is in said predetermined position, the relative position of said rollers with respect to each other and said abutment being such as to maintain said bridging contact in normal current conducting engagement with said stationary contacts after movement to such engagement while said abutment is held in said predetermined position.

13. An electric switch comprising two relatively stationary contacts, a bridging Contact, means supporting said bridging contact in pivotal engagement on one of said stationary contacts and for movement into and from engagement with the other stationary contact, a movable abutment, releasable means for holding said abutment in a predetermined position, a first roller mounted on said supporting means, actuating means comprising a second roller movable on said abutment between the abutment and said first roller and means adapted to be operated to move said second roller on said abutment in a direction to effect engagement of said bridging contact and said other stationary Contact when said abutment is in said predetermined position, and means for maintaining said bridging contact in normal current conducting engagement with said stationary contacts while said abutment is held in said predetermined position.

14. An electric switch comprising a relatively stationary contact, a movable contact, means pivotally supporting said movable contact, a movable surface on said supporting means, a pivotally mounted element having a cam surface of a predetermined contour opposed to the movable surface on said supporting means, releasable means for holding said element in a predetermined position, actuating means for moving said pivotally mounted contact into engagement with said stationary contact when the element is in said predetermined position comprising a member movable along said cam surface and between the cam surface and said movable surface, said member being positioned when the pivotally mounted contact is in normal current conducting engagement with the stationary Contact to maintain said engagement while said element is held in said predetermined position, means in which energy is stored during the movement of the pivotally mounted contact into engagement with the stationary Contact for quickly effecting movement of the pivotally mounted contact away from the stationary contact upon release or said holding means, and means for effecting the release of said holding means.

l5. An electric switch comprising a relatively stationary contact, a bridging contact, means pivotally supporting said bridging contact, a movable surface on said supporting means, a pivotally mounted element having a cam surface of a predetermined contour opposed to the movable surface on said supporting means, releasable means for holding said element in a predetermined position comprising an armature biased to the unattiacted position and a holdin-g Winding for maintaining said armature in the attracted position against the bias thereof, actuating means for moving the bridging contact into engagement with said stationary contact when the element is in said predetermined position comprising a member movable along said cam surface and between the cam surface and said movable surface, said member being positioned when the bridging contact is in normal current conducting engagement with the stationary contact to maintain said engagement while said element is held in said predetermined position, means in which energy is stored during the movement of the bridging contact into engagement with the stationary contact for quickly effecting movement of the bridging contact away from the stationary Contact upon release of said holding means, means for opposing the holding action of said holding winding to effect movement of said armature under its bias whereby to release said element from said predetermined position, means dependent on the movement of the element during the circuit opening movement of the bridging contact for returning said armature to the attracted position, and means for effecting the release of said holding means.

16. An electric switch comprising two relatively stationary contacts, a bridging Contact, means supporting said bridging contact in pivotal engagement on one of said stationary contacts and for movement into and from engagement with the other stationary contact, pivotally mounted element having a cam surface of a predetermined contour, releasable means for holding said element in a predetermined position, a rst roller mounted on said supporting means, actuating means comprising a second roller movable on said cam surface between the surface and said first roller and means adapted to be operated to move said second roller on said cam surface in a direction to effect engagement of said bridging Contact and said other contact when said element is in said predetermined position, said second roller being positioned relatively to said first roller and said cam surface when the bridging contact is in normal current conducting engagement with said stationary contacts to maintain said engagement while said element is held in said predetermined position, means in which energy is stored during the movement of the bridging contact into engagement with said other stationary contact for quickly effecting movement of the bridging Contact away from said other stationary contact upon release of said holding means, and means energizable to effect the release of said holding means.

17. An electric switch comprising a pivotally supported Contact, a cooperating contact, a surfact movable with and relatively to said cooperating contact, a movable abutment having a surface opposed to said movable surface, releasable means for holding said abutment in a predetermined position, and means for moving the pivotally supported contact into engagement with the cooperating contact when the abutment is in said predetermined position comprising a member movable on said abutment surface and between the abutment surface and said movable surface.

WINFIELD A. ATWOOD. 

